Dewatering method



M y 1939. D. M. WRIGHT 2,158,169

DEWATERING METHOD Filed Nov. 23, 1936 lll 'lll HIIII 1M] .DdI/I d MWnigfit INVENTOR ATTORNEY Patented May 16, 1939 UNITED STATES PATENTOFFICE DEWATERING METHOD David M. Wright,.Agricola, Fla., asslgnor toIndustrial Patents Corporation, Chicago, Ill., a corporation of Delaware1 Claim.

This invention relates to'an improved dewatering method.

In mining operations in which large quantities of the mineral values arefound in pieces differ- 5 ing in size from the nonmineral constituentsof the gangue, it is customary to separate the mineral values from thenonmineral values by screens.

In the Florida phosphate fields the pebble phosphate is separated fromthe gangue by washing apparatus employing classifiers of differenttypes, including screens.

One of the objects of the present invention is to provide an improveddewatering method particularly adaptable to phosphate rock washers.Phosphate rock in the Florida fields is hydraulically mined, and it is,therefore, necessary to dewater the rock during the process ofclassification.

Dewatering is one of "the functions of the washer. It is common practicein phosphate rock mining to employ large quantities of water to carrythe matrix from the pit to the washer. The material is delivered at thetop of the washer,

5 and in ordinary practice first passes over a fiat screen with a slopeof about 2 inches to the foot to dewater the material before it entersthe logs. Screens of this type are usually about to 40 feet long.

30 The method of the present invention employs a staged screenarrangement and secures more eflicient dewatering than may be securedwith a conventional dewatering screen.

The drawing is a diagrammatic side view, partly in section, showing oneform of a staged screen arrangement which may be employed in the methodof the present invention.

Material is delivered from the mine to the washer through pipe I, andpasses over a series of three screens. 2. 3. and 4, each of which iscreasin'gly less mobile; 1 each succeeding screenovercomes the tendency20 the series."

about twelve feet long. Screen 2 is provided with a slope oftwo inchesto the foot, screen 3, a slope of four inches to the foot, and screen 4;a slope of six inches to the foot.

The arrangement of screens exemplified in the drawing provides twodistinct advantages in dewatering. In the first place, the stagearrangement gives a redistribution of the material when i passes fromscreen 2 to screen 3, and again when it passes from screen 3 to screen4, which in redistribution aids. in dewatering.

It will be noted that the screens are mounted on aframe work 5 whichalso carries troughs 6. l, and 8 beneath screens 2, 3, and 4respectively to convey water passing through the screens to 13 a commondrain 9.

Since the material is progressively dewatered as itproceedsdown theslopes, it becomes in- The increased slope of of thescreens to clog, andpermit surges of rock to flow over rock blocked at the lower end of thescreen. It is this feature which gives the present invention thepeculiar utility in dewatering minerals.

-It will be understood that one or more of the screen stages may be ofthe vibrating type if desired. Vibration may be imparted througheccentrics or by means of any suitable apparatus.

I claim: I o

A process'for dewatering a 'freely mobile mixture of water and a solidwhich during dewatering becomes increasingly less mobile which con-'sists in passing. the mixture solely under the influence of gravity,over-a series of screens in- 35 clined in opposite directions andarranged one i above the other with the inclination of the screensincreasing from the first to the last of DAVID M. WRIGHT. 40

